To address the practical problem of decreased anchoring effect due to the detachment of the exterior bolt head from the cave wall under dynamic loads, this paper developed a partially recoverable displacement energy absorption (RDEA) bolt. On the basis of preliminary static loading performance tests, a field comparative test was conducted on the blast resistance performance of the cavern reinforced by RDEA bolt. The overall damage and dynamic response of the RDEA-bolt-reinforced test section and the conventional steel-bolt-reinforced test section were compared. The research found that under the same test conditions, the macroscopic damage to the conventional steel-bolt-reinforced test section was more severe than that of the RDEA-bolt-reinforced test section. When the scaled distance was 0.93 m/kg1/3, the ratio of the rebound displacement to the displacement peak at the arch top of the conventional steel-bolt-reinforced test section was 9.09%, while that of the RDEA-bolt-reinforced test section was 31.1%. The energy consumption characteristics of the RDEA bolt were described by the pressure peak value at the third working condition of the arch top. The pressure peak value of the RDEA-bolt-reinforced test section was 76.4%, lower than that of the conventional steel-bolt-reinforced test section. The arch top acceleration of the conventional steel-bolt-reinforced test section was about 1.35 times that of the RDEA-bolt-reinforced test section. The good blast resistance performance of the cavern reinforced by RDEA bolt was reflected from various aspects, such as macroscopic damage and the wall displacement, indicating that the RDEA bolt can not only weaken the effect of explosion load at the cavern location but also enable the reinforced cavern to have a good ability to resist deformation recovery after explosion, thereby having good application prospects.

To investigate the energy absorption capacity of the mixed lightweight aggregate concrete (MLWC), a new device of electromagnetic driving split Hopkinson pressure bar (SHPB) was self-developed, and the numerical model of electromagnetic driving SHPB and the mesoscale model of MLWC were established. Some simulations of electromagnetic driving SHPB impact for MLWC with different gravel replacement rates under different initial voltages were carried out, which were verified by the indoor experiments. Results show that the peak velocity of the bullet is exponentially related to the initial voltage, and the peak velocity has a power function relationship with the power-off time when the bullet reaches the peak velocity. With the increase of gravel replacement rate, the peak value of specific energy absorption for MLWC and the dynamic compressive strength increase gradually, while the absorbed energy density decreases. When the gravel replacement rate is 25-35%, the strength of MLWC is effectively improved on the premise of ensuring its energy absorption capacity. The obtained conclusions can provide a reference for the application of MLWC. Keywords: Electromagnetic drive, Mixed aggregate concrete, Simulation modelling, Split Hopkinson pressure bar (SHPB), Energy absorption